In the context of a home network, it could be desirable to have information on the connection topology of the network. Home appliances are generally organized in a home environment around passive equipment like hubs or switches. Most of the time, these devices do not have any software for remote control and administration, they do not have their own IP address, in one word, they are transparent for the appliances.
However, they are not transparent in terms of network topology and messages propagation. The two main devices that are under consideration here are the hubs and the switches. As shown in FIG. 1a, hubs concentrate all the traffic in one node, i.e. each packet received on any interface is sent to all the other interfaces. As shown in FIG. 1b, a more intelligent work is done by the switch, as the packet are transmitted only on the interface where there could be interested nodes (a unicast packet is routed on the interface where the target is plugged and a broadcast packet is sent to all interfaces). The filtering could be done at the IP or Ethernet level.
Most of the products provided for standard consumers do the filtering at the Ethernet level, and most of the time they are unmanaged. Therefore it is desirable to provide a method to determine the Ethernet topology for the home network that consists of various home appliances organized around hubs and switches.
The most interesting information to extract from the network topology is to know which node of a certain terminal is separated by a switch. In that case, any traffic collision on the Ethernet bus could be avoided, when the target devices connected on a hub send unicast packets.
There are some conventional topology determination methods used in computer network systems, such as Ethernet, Token Ring, or Token Bus networks.
As indicated in European patent application No. EP0892523, a method and system for detection of bridged and repeated network device connections are provided. According to the preceding patent application, the term “bridged network device” is interchangeable with the term “switch”, and the term “repeated network device” is used to extend the length, topology, or interconnectivity of a physical cabling medium, and therefore corresponds the term “hub”. One preferred embodiment of the mentioned invention is accomplished by sending out test packets and noting special qualifiers. To test any given connection, a “priming” packets is initially sent out in case a switch is attached so as to cause the switch to update its address table. A first test packet with identical Source Address (SA) and Destination Address (DA) is then sent out on one link to test if the connection is a repeated loop. Then depending on the testing result of the first test packet, a second packet using a broadcast DA, a multicast DA, or a non-existent unicast DA is sent out for performing testing of a switched connection.
In US patent application of No. US2003/0225916 filed on May 30, 2002, a system and methods for implementing a data link layer communication protocol, such as Spatial Reuse Protocol (SRP) designed for use in a bidirectional, counter-rotating ring network are provided. One embodiment of this invention discloses a topology discovery process which generates a topology map in the form of a doubly linked list reflecting the results. The topology discovery process as claimed in this application comprises steps of transmitting a topology discovery packet; receiving said topology discovery packet after said topology discovery packet is updated by one or more nodes in a network coupled to the computer system; and generating a topology map of the network.
However, both of the above mentioned prior arts are complicated. Moreover, all existing topology determination methods of prior art are also failed to give any inspiration and teachings for the present invention. Therefore, a simple and efficient method for determining connection topology of the home network is greatly desirable.